Green’s Dictionary of Slang

number two n.

[euph.]

1. (mainly juv.) defecation; thus as v. to defecate.

[UK]Farmer & Henley Sl. and Its Analogues.
[US]J.T. Farrell World I Never Made 202: She doesn’t like me in here with you when you’re doing number two. [Ibid.] 348: He had done number two in his pants. Nasty!
[US]H. McCoy Kiss Tomorrow Goodbye in Four Novels (1983) 84: If it was Number Two you had to do you had to rush because come hell or high water, you had only five minutes.
S. Beckett Watt (1988) 118: He might have got up, without the bell’s sounding, to do his number one, or number two, in his great big chamber pot.
[UK]K. Williams Diaries 6 June 191: Of course she’d been doing her number twos in ’em and I told her she was a dirty bitch & ought to have her face smacked.
[US]P. Conroy Great Santini (1977) 344: ‘He’s going number two,’ Mary Anne said with delicacy.
[Can]M. Atwood Cat’s Eye (1989) 230: They’ve rationed the toilet paper [...] Four squares a time, even for Number Two.
[Aus]M. Walker How to Kiss a Crocodile 57: I was told that it would be about four days before I looked like getting to attempt number twos. When I did try number ones, I strained, grunted and groaned as I hovered over the porcelain bowl.
[UK]K. Lette Llama Parlour 92: Well, Jesus, ya know, takin’ the first cra . . . doing number two’s with a lover a round. I mean. That’s a big step.
[UK]L. Gould Shagadelically Speaking 31: [He] asks Austin for a courtesy flush after hearing what he presumed to be Austin’s struggle with an altogether different type of Number 2.
[UK]Guardian G2 29 Mar. 17: Your number twos are also likely to be ‘more loose’.
[UK]S. Kelman Pigeon English 97: Number two is another name for a shit.
[US]J. Stahl OG Dad 73: Just pretend you’re on an airplane and you need to Number Two, but all the restrooms are occupied.
[UK]A. Wheatle Crongton Knights 8: ‘Tell them to ram their interest where the number two hides’.
[Aus]T. Spicer Good Girl Stripped Bare 154: ‘Look, Mummy, I did a nice “number two” next to the lounge’.

2. (W.I.) a large round dumpling [it is indented around its circumference to facilitate splitting it in half, but note sense 1].

[WI]cited in Cassidy & LePage Dict. Jam. Eng. (1980).

3. (orig. milit.) second-in-command, second in rank.

[UK]Manchester Guardian Weekly 25 Apr. 17: The US as number one super-Power. It just does not pay to be number two.
[UK]L. Gould Shagadelically Speaking 34: His eye-patch-wearing second-in-command, Number 2.
[UK]N. Barlay Hooky Gear 14: His number 2, Arno, wheezy old dickhead twice his age, play solitaire on a packin crate.